The present invention relates to an electric power supply device for a hand or pointer which carries an electric load.
The present applicant has proposed an electric power supply device for a hand with load or pointer with load in U.S. patent application Ser. No. 407,408. This device is constructed as described below.
Two annular conductors are disposed around the center of rotation of a hand or pointer below the hand. A pair of contact members each of which has a contact capable of sliding on one of the annular conductors is mounted on the underside of the hand. The annular conductors are electrically connected with an external circuit. The contact members are electrically connected with a load on the hand.
In operation, when electric power is supplied to the two annular conductors from the external circuit, the two contact members are electrically connected by the contacts sliding on the annular conductors. Then, electric power is supplied to the load.
In the aforementioned prior art structure, when the contacts slide on the annular conductors, they produce resistance to the rotation of the hand. If the pressure applied to the conductors by the contacts is reduced to decrease the resistance, then the reliability of the electrical conduction may be deteriorated. Therefore, it is necessary to take care in machining and assembling the contacts. Also, it is cumbersome to execute these operations. Further, it is necessary to mount the contacts to the hand in such a way that they are placed in a predefined position. In this way, it is laborious and cumbersome to manufacture hands or pointers.